Mac: Focus issues when embedding into non-Qt apps

We use Qt to embed controls into floating palettes of Adobe Illustrator. An Illustrator-provided palette is the parent of Qt widgets. There are multiple issues with transfering focus between Qt controls and Adobe controls:

• Qt edit fields sometimes not get focus
• Qt edit fields sometimes not lose focus, esp. when Adobe controls get the focus
• Text caret sometimes not shown when typing in a Qt edit-field

The root-cause is that the container widget was not activated after mouse clicking. The 'QCocoaWindow' should handle the window de/activation if it's embedded (i.e not a toplevel NSWindow).

The proposed fix is in QCocoaWindow::windowDidBecomeKey() and QCocoaWindow::windowDidResignKey() - see the attached patch file for Qt 6.3.1. 6.3.2, 6.6.0